1. Technical Field
The present invention relates generally to a dietary supplement composition which has lipid binding properties and, more particularly, to a composition that includes aloin (especially aloe saponins) and an amino polysaccharide such as, for example, chitosan.
2. Background
It is known that obesity and hyperphagia, or excessive eating, are both problems with behavioral and physiological components. It is also known that one drawback of some diets is that they do not work effectively on people with excessive appetites. The constant feeling of hunger in such people disturbs their daily activities. People suffering from appetite disorders are also often subjected to pyrosis or gastric burning (heartburn) and a sensation of acidity in their stomachs when not eating.
Chitin is an amino polysaccharide (poly-N-acetyl glucosamine) found in the exoskeleton of arthropods (e.g., crustaceans such as shrimp, crab and lobster; insects; and molluscs). The exoskeleton is the hard outer covering that functions as the mechanical supporting tissue of the body structure of such animals. Chitin is also found in some plants and fungi.
Chitosan is a natural product that can be derived from chitin, and is typically prepared by direct deacetylation of chitin in a caustic solution. Chitosan is a biopolymer similar in structure and properties to dietary fiber (e.g., vegetable bran, cellulose) but with additional dietary or nutritional advantages which are derived from its polycationic, or positively charged, structure. From a chemical standpoint, chitosan consists of polymerized D,L-glucosamine which is insoluble in water and in most common organic solvents. Unlike plant fiber like bran and cellulose, chitosan has the ability to absorb fat and other lipids in the intestine.
Chitosan also exists as a salt, and a number of chitosan salts are known and described in the literature. For example, N,O-carboxymethyl chitosan (NOCC) is obtained by reacting chitosan with monochloroacetic acid under alkaline conditions. The salts of chitosan generally show good solubility in water (e.g., acetate, citrate, formate and tartarate salts as described in U.S. Pat. No. 4,363,801).
Chitosan-lipid complexes are formed through bonds which can be attributed to the density of positive charges on chitosan. Due to chitosan's indigestibility, lipid absorption by the intestine is reduced. These characteristics make chitosan helpful in the treatment of high blood fat, hyperlipemia and high blood cholesterol, hypercholesteremia or hypertriglyceridemia. Through such complexes, chitosan is able to reduce the amount of lipid and cholesterol available for absorption and assimilation by the body.
One disadvantage of using chitosan for the aforementioned purpose is that it induces constipation, an undesirable condition that includes difficult and often painful elimination. Hence, the use of chitosan as a dietary supplement must be of a short duration or other ingredients or supplements added to combat the undesirable effects of the chitosan. U.S. Pat. No. 4,999,341 discloses the use of chitosan with soy saponins. The patent discloses combining soy saponins with chitosan so that the diarrhea-inducing soy saponins offset the constipating effect of chitosan. Other plant sources of saponins are listed in Table 1 of U.S. Pat. No. 5,370,890.
The present invention is directed to a dietary supplement that includes chitosan, or a functionally acceptable equivalent thereof, and aloin. Aloin contains aloe saponins which act as a laxative to offset the constipating effect of chitosan. However, aloe saponins have benefits not available from soy saponins in formulating the dietary supplement which include activities in the upper and lower gastrointestinal tract. In the upper gastrointestinal tract, aloe saponins act to increase desirable properties of chitosan: surface activating properties are increased to improve dispersion of chitosan and its capacity to bind fat, gel density is increased, and gel viscosity is increased. Furthermore, in the lower gastrointestinal tract, a laxative activity of the composition is produced locally by hydrolysis of barbaloin, a component of the aloe saponins, to aloe emodin which acts as a laxative by increasing water retention and mucus secretion in the large intestine. These and other beneficial properties of the present invention are further described below.